Activity Shielding The Solar Panels

This experiment uses the same circuits from the previous experiments to read the solar panel voltages. A cardboard hood and a servo will be added to the solar panels, and the servo will be connected to the board. You will also need the following household (or school-room) items that are not included in the kit:

• Cardboard box or sheet of heavy paper for a hood

Before mounting the solar panel to the servo it will first be necessary to add a box-like hood around the solar cells. The reason for this is to block out any sidelight that will affect the voltages being generated by both the left and right solar panels. In effect, the hood will act to "tunnel" the light coming directly from the sun onto the solar panels. This will make tracking the sun a lot more precise, since the hood greatly reduces reflected side lighting. You can use any convenient material like cardboard or rigid construction paper to make a hood. We used corrugated cardboard for our example.

V Construct a simple box out of heavy paper or cardboard by bending a strip at least 4 inches wide (the longer the hood, the better the light tunneling) around all four edges of the solar panel tray and taping it in place.

V Make sure to surround the tray on all sides and make a notch for the triangular protruding section.

V Take some time to do this because you will want the hood to remain in place for several days, or longer, as you experiment with the sun tracker. Refer to Figure 4-8 for some ideas.

V Make sure to surround the tray on all sides and make a notch for the triangular protruding section.

V Take some time to do this because you will want the hood to remain in place for several days, or longer, as you experiment with the sun tracker. Refer to Figure 4-8 for some ideas.

Figure 4-8: Adding A Hood

With the hood in place it's now time to test it effects using StampPlot.

V If you disconnected your solar panels from your circuit to tape on the hood (which you probably did) reconnect the leads now, referring back to Figure 3-4 on page 91.

V In the BASIC Stamp Editor, run DuelingSolarCells.bs2.

V Make note of the COM port in use, and then close the Debug Terminal.

V Open StampPlot via Start ^ Parallax Inc ^ StampPlot ^ Experiments with Renewable Energy ^ sic_ewre_exp_3.spm. (If StampPlot is already open, you may select Macros from the toolbar, then Select Start-Up macro, and open sic_ewre_exp_3.spm from the SIC_Energy folder.)

V Hold the hooded panel in your hand and point it at the sun or a bright light.

V Move the panel back and forth across the light source, then hold it underneath the light source and tilt the tray from side to side.

Notice how the voltages peak then fall off when the solar panels are not pointing directly at the light source, visible in the first two peaks on left side of the plot in Figure 4-9. Following that, the two channels show greater separation when tilting the solar panels from side to side. This voltage difference between the two channels will be used by the sun tracker program to direct a servo motor to turn the panels toward the light source.

Figure 4-S: Voltage Outputs From Hooded Solar Panels

Your results will vary depending on the color, transparency and reflective qualities of the material you use for the hood. Indeed, experimenting with different materials could be another avenue of exploration. Nevertheless, try to design your hood to be as deep as possible to help make the sun tracking experiment produce quickly-changing voltage peaks and valleys, which demonstrate the effectiveness of the hood's tunneling effect. You should also view the left and right LEDs on your circuit to confirm that they both illuminate ONLY when the hooded solar panels are pointed directly at the light source.

V If you are going to continue on now, click on the Disconnect button in StampPlot so you can run a new program in the BASIC Stamp Editor.

Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.